Furnace control



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E. MGLEAN FURNACE CONTROL Original Filed June 25, 1920 4 Sheets-5heet :5

BY Y 5 v LM A TTORNEY March 16 1926.

E. MCLEAN FUnNAcE CONTROL Original Filed June 25, 1920 4 Sheets-Sheet 4'INI/ENTOR.

WITNESS:

4 l a if ATTORNEYS Patented Mar. 16, 1926.

UNITED STATES PATENT OFFICE.

EMBURY MCLEAN, OF BROOKLYN, NEW' YORK, ASSIGNOR TO THE ENGINEER COM-PANY, or new YonK, N. Y.,

A CORPORATION OF NEW YORK.

FURNACE CONTROL.

Application led June 25, 1920, Serial No. 391,779. Renewed April 22,1925.

T all whomA t may concern.'

Be it known that I. EMBURY MCLEAN, a citizen of the United States, andresident of the city of New York, borough of Brooklyn, in the county ofKings and State of New York, have invented certain new and usefulImprovements in Furnace Controls, of which the following is aspecification.

My invention relates to new and useful improvements in the control ofcombustion in fluid-fuel-burning` furnaces, and more particularlyrelates to a method for controlling the elements of combustion in such afurnace.

One object of the invention, among others, to be described hereinafter,is to provide an improved method for controlling the amount of airsupplied to a fluid-fuel-burning furnace so that said air may be variedto meet the requirements of combustion, the control being effected bythe rate of flow.

The invention also contemplates an improved method for controlling theair fed to the furnace in such manner that a uniform mixture of thefluid fuel and air is obtained for the varying conditions of the flameinthe furnace chamber.

The invention consists in the improved method to be more fully describedhereinafter, and the novelty of which will be particularly pointed outand distinctly claimed.

I have fully and clearly illustrated certain apparatus for practisingthe invention in the accompanying' drawings to be taken as a parthereof, and wherein:

Figure 1 is a view in side elevation, partly in section, of a steamboiler furnace for practising said invention.

Fig. 2 is a, horizontal section taken through Fig. 1, with portionsbroken away to show other parts in section, and other parts being shownin plan.

Fig. 3 is a view in side elevation, partly in section. of a steam boilerfurnace showing another embodiment of my invention.

Fig. 4l is a transverse section through a controlling device employed inthe embodiment shown in Fig. 3, wherein said device is operated by therate of flow of oil fed to the burner to control the air supplied forcombustion to the furnace.

Fig. 5 is a plan view of the lower portion or h alf of the device shownin Fig. 4.

Fig. 6 is a top plan view, partly in section, of the upper portion orhalf of the element shown in Fig. 4l.

Fig. 7 is a vertical central section through the pressure controlleddevice constituting one of the elements of the form of the inventionshown in Figs. 1 and 2, to control the air supplied to the furnace forcombustion, by the pressure of the fluid fuel fed to a burner.

Fig 8 is a top plan View, partly in section, showing in detail certainof the elements in Fig. 7.

Fig. 9 is a vertical longitudinal section through a regulator forcontrolling the quantity of fluid fuel fed to the furnace in accordancewith the steam pressure of the boiler, and also to control the amount ofatomizing steam fed to the burner to atomize the oil flowing therefrominto the furnace.

Fig. 10 is a detail view of a portion of the inlet air damperconnections shown in Figs. 1, 2 and 3.

Fig. 1l is a view in front elevation, partly in section, of a regulatorfor controlling the furnace gas pressure.

Fig. 12 is a central vertical section of the regulator shown in Fig. 11,and

Fig. 13 is a detail view, partl in section, showing the arrangement ofampers for controlling access of air to the furnace chamber.

I will first describe in detail the apparatus shown in the accompanyingdrawings and then, in connection with a description of the operationthereof, setforth the novel method, a l of which constitute myinvention.

Referring to the drawings by characters of reference, and particularlyto Figs. 1 and 2, 1 designates a boiler furnace of any wellknownconstruction, and to which my invention is applicable, it beingunderstood that said furnace is shown merely by way of example, and thatmy invention is not limited to the type or construction of said furnace.

In the type of boiler furnace shown, said furnace is provided with sidewalls 2, 2. front wall 3, a rear wall 4t, and a bridge wall 5, which,together with the fronit and side walls form a furnace chamber 7, thetop of the furnace chamber being formed by the lower surface of theboiler or boiler tubes (not shown), an upper steam drum of which isshownl at 6. Iithi'n the furnace chamber and spaced vertically from thebottom or floor of the furnace, is a substantially horizontal partition8 extending from the front wall to the bridge wall, and from one sidewall to the other, so as to provide an air inlet chamber 9 beneath saidpartition. An area or portion of said partition is of open-work orchecker-work structure so as to provide a plurality of openings throughwhich air may flow from the chant ber 9 to the furnace chamber 7, saidarea being substantially coextensive with the size of the flame when theburner is working at high pressure. By reference to Fig. 2, it will beseen that the checker-work portion is of flaring form, the taperingsides of which are provided by imperforate portions 11 of saidpartitions at the forward corners of the furnace, the outwardly inclinededges 12 of said imperforate portions defining the forward boundaries ofthe flaring checker-work portion. In the present embodiment the saidfia-ring edges 12 extend from a point adjacent the center of the frontwall to a point substantially midway the length of the side walls of thefurnace, so that the checker-work extends from said boundaries rearwardsto the bridge wall lengthwise of the furnace, and the entire width ofthe furnace at poinrts in rear of the points at which said boundariesmerge with said side walls. It will be seen that the area of theopen-work portion of the partition 8 conforms substantially to themaximum form of the flame in the furnace chamber.

The furnace is also provided with a suitable outlet stach 18 throughwhich the products of combustion find exit, the area of the passagethrough the stack being controlled by a suitable damper 14 pivoted, asat 15, on the stack, in any suitable manner.

The means for supplying fiuid fuel to the furnace consists of a burneror nozzle 16 located preferably in the front portion of the furnacechamber above the partit-ion 8 and central of the transverse width ofth-e furnace chamber, and over the forward portion of the open-work areaof said partition. This burner or nozzle may be of any well-known typefor feeding fluid fuel in admiXture with an atom-izing element, such assteam or air, to the furnace chamber. Oil or other fluid fuel is fed tothe said burner from a pump 17 through a pipe 18 controlled by a shut-odvalve 19, and steam under pressure from the boiler is fed to the burnerthrough a pipe 20, the latter containing valves 21, 21. The quantity offluid fuel and atomizing steam flowing to the burner through pipes 18,20 is controlled by a regulator, shown generally at 22 in Fig. 1, andspecifically in Fig. 9, operating valves in the fluid fuel and steampipes, the valve in th-e latter being located between the hand-valves2l. rI his regulator ma),Y be of any suitable type which can be adjustedso as to automatically regulate the amount of oil fed to the burner inaccordance with the steam pressure of the boiler.v and also the quantityof steam fed to the burner to atomize the oil. In the drawingsl (seeFig. 9), I have shown a well-known type of regulator for thislliur'pose, the same consisting of a cylindrical chamber havingdiaphragm heads 24, 25 sealing the chamber, the latter being connectedby a pipe 26 with a source of Isteam at boiler pressure. Over thediaphragm 24 is a plate 27 supporting a frame 28 connected on its upperend, 1n any suitable manner, to a valve body or casing 29 located in thesteam pipe 20 between the valves 2l, as stated, said body having a valvescat 8O with. which cooperates a valve 3l connected to a stein 32 guidedby a stulling box 33. and a sleeve 34, the latter being threaded in thesaid frame 28, as at The valve stem 32 is connected to a plate 36resting on the diaphragm 24, heretofore described. Surrounding the stein32 is an expansion spring 87, the ends of which respectively abut thesaid plate 86 and an abutment 88 resting against the lower end of saidsleeve 34, the function of said spring being to urge the valve 3111nward open position in opposition to the pressure of steam within thechamber 2), The pressure of the spring 87 may be regulated by adjustingsaid screw 34 and consequcntly the position of the said plate 258 sothat the latter may be adjusted relative to the plate 36 to compress errelieve the compression of the spring 87 A construction similar to theabove is provided for regulating the quantity of fluid fuel, andincludes a valve body or casing S9 in the pipe 18 having a seat 40having a passage controlled by a valve 41, the latter being connected toa stein 42 guided through a stuffing box 43 corresponding to thestuffing box 33, heretofore described, and supported by a frame 44supported by a plate 45, similar to the plate 27, heretofore described.The stem 42 is guided through an adjustable screw 46 threaded through aportion of the frame` as at 47, and carrying an abutment plate 48against which abuts one end of a spring 49 coiled about the said stein42, and the other end of which is connected to the plate 50 on the outerface of the diaphragm 25. This spring normally urges the valve 41towards open position in opposition to the steam pressure within thechamber 23 tending to close the valve. By adlll) justment of theelements 34- and 47, heretofore described, the relative area of theopening in the steam pipe and the oil supply pipe may be regulated inaccordance with a given steam pressure in order to determine the amountsor quantities of oil and steam fed to the boiler.

Connected to the oil supply pipe 18, as at 51, is a pipe 52 leading to aregulator, shown generally at 53 in Figs. 1 and 2, which is actuated inaccordance with the pressure of the oil in said pipe 18 to regulate thedampers, hereinafter described, so that the quantity of air fed to thefurnace will be varied in accordance with a characteristic of flow ofoil fed to the boiler, in this instance, the characteristic of flowbeing the pressure of such oil. Said regulator' will be specificallydescribed hereinafter.

The fluid fuel fed from the burner or nozzle 16 to the furnace chamber 7being under pressure is in the form which results in a iianic which iseither substantially cone-shaped or fan-shaped, according to the type ofburner employed. It is desirable that the air entering the furnacechamber be admitted over an area conforming as nearly as possible to theform or area of the flame in order that the best results be obtained asregards complete combustion. My invention provides an ellicient meansfor regulating the area of air distribution, and for this purpose Iprovide means for controlling the area of the open-work portion of thepartition 8 through which the air flows from the space 9 to the chamber7, so that said area will conform substantially to the area of theflame, and will supply a quantity of air desirable for combustion. Forthis purpose I divide the chamber 9 into a plurality of air chambers,each preferably having an independent air supply, and having outletsupwards into the furnace chan'iber through that portion of the openworltpartition 8 in'iniediately over the particular chamber beneath saidpartition. In the present einliodin'lent, I preferably divide chamber 9into three such air supply chambers, and do this by providing twovertical partitions 511 extending in a general direction lengthwise ofthe furnace and having their inner ends closely adjacent each other toprovide a passage, as at 55, adjacent the nozzle 16 from which pointthey Hare outwards to the point where they abut or join the bridge wall5, as shown at 56. The inner ends of said partitions 54. are connectedby outwardly directed end partitions 57 with the side walls of thefurnace, respectively. The partitions 54 and 57 eX- tend from the floorof the furnace to the underside of the partition 8, so as to form threeseparate independent chambers. It

will be seen that by the arrangement of partitions 54 and 57, the spacebeneath the partition 8 is divided into a. central flaring chamber 58and two wing compartments 59, said central chamber being approximatelythe shape and area of the flame when the burner is being operated at arelatively low pressure, and the air through the open-work portion ofthe partition 8 from the wing compartments 59, 59 being available for anincreased area of the flame when the burner is operated at relativelyhigh pressures. It will thus be seen that I am able to control the areaof air supplied through the partition 8 in order to conformsubstantially to the area of the fiame when the burner is operated atdifferent pressures. As stated, I preL-"erably provide independent meansfor controlling the supply of air to each of the chambers and 59, suchmeans preferably consisting of dampers 60, 61, 62, the same beingpivoted` respectively in the passage between the inner ends of the walls54:, and the dampers 61 and 62 being pivoted in openings 63 and 64 inthe said partitions 57. In the present embodiment, I provide means forautomatically operating the said dampers in order to control the supplyof air to the chambers 58 and 59, in accordance with a characteristic ofthe flow of oil to the burner. I desire it understood, however, that myinvention, as regards the method of air distribution to conform to thearea of the fiame, is not limited to any particular means forcontrolling the amount of such supply, as such amounts may be regulatedby either automatic or hand-control. In the present embodiment where thedampers are automatically controlled, the dampers 61, 62 are mounted onhorizontal shafts 65 mounted in suitable bearings, carrying levers 66,each of which is provided on its end with a weight 67, said weightnormally tending to rotate the shafts to move the dan'ipers to openposition to increase the amount of air fed to the chambers 59. Thedamper is mounted on a shaft 68 connected by a universal joint 69 withone or both of the said shafts 65, so as to move all three of saiddempers in unison. The connection between the central damper 60 and thedainpers 61 and 62 is so adjusted that when the dampers 61 and 62 areclosed, the central damper will be partially open, so as to admit air tothe central chamber 58, but as the dempers 61 and 62 are moved towardopen position, the damper 60 will be moved to increase the area of theopening controlled thereby to the chamber 5S. Air is admitted to thefront portion of the furnace beneath the partition 8, and in front ofthe walls 57, through an air duct 70 in the front wall of the furnace.The duct 70 may be open to the atmosphere, shown, or be connected to asource of draft under pressure, as for example, a blower. I willhereinafter describe two forms of llt) liu

automatic means for controlling the said dainpers.

The controller 53, heretofore mentioned, operates a flexible connection71 extending upwards over a sprocket 72 on one end of a horizontal shaft73 in suitable bearings above the furnace, and thence downwards and isconnected to one of the said levers 66. On the opposite end of the shaft73 is a sprocket 74 over which extends a sprocket chain 75, one end ofwhich is connected to the other lever 66, the other end of said chainbearing a weight 76, by means of which said chain is maintained taut.The arrangement is such that when the pressure of oil flowing to theburner is increased, said regulator 53 will be actuated to move thedampers to increase the quantity of air flowing to the air distributingchambers, whereas, on the other hand, upon the reduction of the pressureof oil fed to the burner, said regulator will operate to cause saiddampers to be moved toward closed position to reduce the amount of airfed to the distributing chambers in accordance with the pressure of oilfed to the burner, so that the air supplied and distribution thereof ismaintained commensurate for proper combustion. The regulator 53 may beof any well-known type which will serve the purpose and perform thefunctions set forth,but I prefer to employ what is known on the marketas the Mason compensating regulator which is shown in detail in Figs. 7and 8 of the drawings. As this construction is well-known, l do not deemit necessary to describe the same with particularity, but in order thatthe operation thereof may be understood I brietiy describe theconstruction as follow/S177 designates aplate having a diaphragm chamberclosed at its upper portion by a flexible diaphragm 78 upon which restsa plate 79 upon which is mounted a fulcrum 80. The chamber 77Il formedby the plate 77 and the diaphragm 78 is connected to a pipe 52,heretofore described. Supported over the diaphragm chamber is aframe 81supporting a downwardly directed knife-edge fulcrum 82 against whichbears a fulcrum pin 83 on one end of a lever 84, said lever also havinga fulcrum bearing as at 85 on the said fulcrum 80, so that said leverresponds to movements of the said diaphragm 78 in accordance withvariations of pressure in the diaphragm chamber 77a. The outer end ofthe lever 84 carries a weight 85 opposing the pressure exerted by thediaph 1agm 78 tending to lift the lever 84. This lever 84 controls theflow, of a. motive fluid to a motor cylinder for operating the chain orflexible connection 71, heretofore described. This motor cylinder isshown at 86 containing a sliding piston 87 mounted on a piston rod 88extending through a stuffing box 89 in one end of the cylinder andconnected, as at 90, to the said chain 71. Within the cylinder 86 areinlet ducts 91, 92, opening on opposite sides of the piston 87 andcommunicating through ducts 93, 94 with a valveway 95, within whichreciproeates a double-headed piston valve 96 on a stem 97 extendingthrough a stuffing box 98 on the casing of the piston valve and operableby means of the lever 84, as will be presently described.

Entering the valveway 95 is a supply opening 99 leading from al suitablesource of fluid pressure, for example, water, an l. above and below thepiston valve 96 are exhaust chambers 100, 100a leading to an exit orexhaust 1001), said piston valve 96 being operable to control the flowfrom the inlet 99, and to the exhaust chambers relative to the saidcylinder 86. lhenaid piston valve is in the position shown iii-Fig. 7,flow of motive fluid is cut off both to and from the cylinder 86, theheads closing the ports 93, 94. Then the piston valve moves downwards touncover the port 93, flow will be permitted from the inlet 99 betweenthe heads of the piston valve 96 to the passage 94, and thence throughthe passage 92 to the cylindcr 86 below the piston 87, and at the sametime. the exhaust 100b will be connected to the upper part of thecylinder 86 through the chamber 100 and the space above the upper headof the double-headed piston valve 96. On the other hand, when the pistonvalve 96 moves upward, the upper portion ot' the cylinder 86 isconnected to the inlet through the passage 93 and the space between tlieheads of the piston valve 96, and the lower portion of the cylinder isconnected to the exhaust through the duct 94, the chamber 100a and theduct or by-pass 101, shown in dotted lines leading to the exhaust 100.The piston rod 97 is pivotally connected at its upper end, as at 102, toone end of a lever 103, the opposite end of which is slotted as at 104(see Fig. 8), and receives an eccentric pin 105 on a shaft 106 havingbearing, as at 107, in a bracket 108 on the cylinder 86, the oppositeend of said shaft 106 being rigidly connected to a lever 108 which, inturn, is pivoted, as at 109, to one end of a link 110, the other end ofwhich is pivoted, as at 111, to the piston rod 88. The lever 103 isconnected, as at 112` to one end of a link 113, the other end of whichis connccted, as at 114, to the lever 84. lVhen the lever 84 raises thepiston valve 96, pressure is admitted to the upper end ofthe cylinder,as described, to move the piston 87 downwards: this causes a downwardmovement of the link 110 which lowers the lever 1083, and throughconnections 104, 105 raises the adjacent end of the lever 103, which,acting on the connection 112 as a fulcrum, moves the double-headedpiston valve 96 towards position to shut off the ports 93, 94. Upon areduction of pressure in the chamber 77",

the weight 85 moves the lever 84 downwards to thereby control the flowto admit pressure to the lower portion of the cylinder 86, causing thecompensating mechanism to operate in the opposite direction Jfrom thatjust described. In designing this regulator, length of leverage betweenthe pin 105 and the shaft 106 can be so proportioned that the regulatormay be caused to operate over any desired range of pressures.

The invention also includes control of the furnace gas pressure. so thatthe latter is maintained substantially7 constant for varying rates ofair supply, this being effected by controlling the outflow of gases fromthe furnace. In order to accomplish this result, I provide the furnacewith what is known as a balanced draft regulation operating inaccordance with the principle described in my prior United StatesLetters Patent No. 817,438, dated April 10, 1906, and No. 826,348, datedJuly 17, 1906, the regulator shown in the present application being ofthe same general construction as shown and described in my prior PatentNo. 1,071,771, dated September 2, 1913. This regulator is shown indetail in Figs. 11 and 12. In these figures, 115 designates arectangular frame set in an opening in one of the side walls of thefurnace chamber and providing an opening between the furnace chamber andthe external atmosphere. In this rectangular frame is arranged aswinging rectangular plate 116 fulcrumed at a point adjacent its lowerend, as at 117, to the side members of the said frame 115. This fulcrumis located preferably at or close-ly adjacent the center of gravity ofthe plate, so that the said plate will remain stationary on its fulcrumat any point to which it may be moved. In order to insure the axis beingthrough the center of gravitation of the plate 116 weight 118 issupported on the lower portion of the swinging plate, said weight beingadjustably supported and held by upper and lower nuts 119 on threadedrods 120 secured to the lower portion of the said plate. The movement ofthe plate on its fulcrum is opposed by upper and lower tension springs121, 122, the former being connected at its lower end to a projection123 on the lower end of the swinging plate, and at its opposite end toan adjustable anchorage consisting of an eye or hook 124 on a threadedshank 124a extending slidably through a bracket 125 secured to the sideframe 115, said threaded shank being adjustably held by means of upperand lower nuts 126, whereby the tension of the spring 121 may beadjusted. The lower spring 122 is also connected at its upper end to thesaid arm or projection 123, and its lower end is connected to a hook oreye 127 having a threaded shank 128 extending slidably through anopening in a bracket 12.9 on frame 115, said shank being adjustablerelative to said bracket by means of nuts 130, whereby the tension onsaid lower spring may be regulated. These springs serve to oppose theswinging movement of the plate, and may be regulated to balance theaction of any draft pressure in the furnace. The movements of thepressure regulator are employed to control the position of the stackdamper 14 so as to control the rate of outflow of furnace gases throughthe stack.

In order to accomplish this result, I provide a pilot valve 131 havingan inlet 132 connected by a pipe 133 with a source of fiuid underpressure, and a combined inlet and outlet 134 connected by a pipe 135 tothe lower end of an operating cylinder 136 containing a piston 137connected to a piston rod 138, which in turn is connected by a flexibleconnection 139 with a` lever arm 140 for operating the damper 14, saidfiexible connection being passed over an intermediate guide pulley 141.The pilot valve is provided with a piston valve 142 connected loosely toa bracket arm 143 on the lower portion of the swinging plate 116. Thepipe 133 is connected by a 'pipeI 144 to the upper end of the cylinder136, above described. The pipe 133 contains hand valves 145, 146, onopposite sides of the connection with pipe 144, and the pipe 135contains a hand valve 147. The pilot valve casing is provided with an.escape opening 148 at its lower end.

The operation of said pilot valve is to control the flow of fluidpressure to and from the lower end of the cylinder 136 in order tooperate the piston 137 to control the damper 14. On the lever 140 is aweight 149 normally tending to hold the damper in open position. Theconstruction of this pilot valve is specifically shown in F ig. 11, butI do notl deem it necessary to describe the same with greater detail, asit is of wellknown construction, and specifically does not form a partof my present invention.

The function of this regulator is to maintain a substantially constantpressure of furnace gases in the furnace chamber for the varying ratesof air supply entering the furnace chamber for the purposes ofcombustion. In performing this function the regulator acts as follows:Should there be an increase of pressure in the furnace chamber abovenormal, the increase of pressure moves the plate 116 outwards, operatingthe pilot valve to control the fiow of motor fluid to the cylinder 136to cause the damper 14 to be moved to increase the rate of outflow ofgases through the stack, thereby reducing the pressure within thefurnace chamber. If, on the other hand, there should be a decrease offurnace gas pressure below normal, the said plate 116 will be movedinwards (to the left in Fig. 12) by the external atmospheric pressure,which movement will operate the pilot valve to control the flow of fiuidunder the piston to flow from the cylinder back through pipe 135 and outthrough the vent 148, thereby causing the damper 14 to be moved toreduce the area of the stack outlet, and thereby increase the pressureof gases within the furnace. IVhen the pressure is relieved under thepiston 137, as just described, said piston is moved downwards by fluidpressure supplied to the upper end of the cylinder through the pipe 144,this pipe being in constant communication with the source of fluidpressure. The use of the balanced draft regulator 116 is an importantfeature of my present invention, as it maintains a constant draftpressure in the furnace chamber. Therefore, for any given area of airdamper openings 55, 62, G3, there will be a given rate of flow of airthrough the damper opening 1?, whereas, if the furnace pressure varied,the amount of air which would pass through a given area of damperopenings 55, 62, 63 would vary with the draft pressure in the furnace.As the area of air opening at 55, G2, 63 corresponds with the pressureof oil supplied to the burner, the dampers 60, 61 and 62 can be adjustedto be operated by the regulator 53 to give any desired rate of flow ofair for the corresponding pressure of oil to the burner.

Applicant is aware that. it has been proposed to regulate the air supplydamper, and the stack damper in accordance with the variations of thepressure of oil to the burner, but such construction will not accomplishthe result of applicants invention, because it will not maintain asubstantially uniform draft pressure in the furnace, due. to the factthat a given position of the flue damper in accordance with the oilpressure will not produce the same draft pressure in the furnace chamberfor all conditions of running the furnace. For a given position of theflue damper, the draft pressure in the furnace chamber will vary withthe draft of the chimney which varies with atmospheric conditions, andin plants where there are two or more furnaces connected to one chimney,the draft of the chimney is varied by the operation of the other furlnaces, and the draft pressure in the furnace is also varied by theinternal resistance of the furnace or boiler, due to accumulations offlue dust and ashes. In all of these conditions my invention maintains asubstantially constant draft pressure in the furnace chamber for allrates of combustion.

The maintenance of a substantially uni form pressure in an oil burningfurnace is vastly more important than it is in a coal burning furnace,because the resistance of an oil burning furnace is very low,practically zero, whereas, the resistance of a bed of fuel is veryconsiderable. If 1/10th of an inch minus draft pressure. would supplythe requisite amount of air for an oil burningl furnace or a fluid fuelburning furnace, and say 2 inches of draft pressure was necessary tosupply air to an ordinary coal burning furnace, a variation of 1/10th ofan inch in the draft pressure would double the variation in the airsupply to the fluid fuel burning furnace, whereas, it would only varythe air supply to the coal burning furnace l /Qllth It is thereforeapparent that a construction which provides a fixed position for theflue damper corresponding to any given pressure of oil to the burnerwill not maintain a substantially uniform pressure of furnace gases forvarying rates of combustion, on account of thefluctuations in the draftof the chimney, due to atmospheric conditions, and due to variations infurnace conditions in other furnaces connected to the chim1'1ey,if any,and due to variations in resistance of the furnace and boiler on accountof accumulations of soot and ashes which vary from day to day. rFliesevariations in a fluid burning furnace amount to as much as the totaldraft pressure necessary for varying combustion. Instead of operatingthe damper 14 to control the rate of outflow of furnace gases, anequivalent would be to employ an induced draft fan connected to thestack and driven by an engine, the controlling valve of which would beregulated by the cylinder 13G.

In Fig. 3 I have shown another embodiment of the same broad invention,heretofore described, but instead of controlling the supply of airflowing into the furnace in accordance with the. pressure of oil fed tothe burner, I effect such control in accorda-nce with the rate of flowoiI oil fed to the burner. In Fig. 3 I show the same structure as to thefurnace proper as shown in Figs. 1 and Q, and also the saineconstruction of the means for maintaining a substantially constantpressure of furnace gases in the fire chamber, and therefore need notagain describe these, as the previous description will be sufficient. Inthis form of the invention the burner or nozzle is shown at 16a, thesame being supplied with steam under pressure through a pipe 20a, and byoil fed thereto by a pipe 52" supplied with oil under pressure from anoil pump 1T. The amount of flow of oil and atomizing steam may becontrolled by a regulator 22 corresponding` to the regulator 2Q, andoperating in the same manner as heretofore described. In this form ofthe invention, however, I provide means responsive to variations in thevolume of flow to efi'ect the automatic operation of the damperscontrolling the flow of air into the furnace, such regulator being showngenerally at 53 in Fig. 3, and specifically in Figs. 4;, 5 and (3. Aswill be seen in Fig. 3, the regulator is interposed in the pipe 52aleading from the pump 172L to the burner or nozzle.

Referring' to Figs. 4, 5 and 6, the construction and operation of saidregulator 53a will be described as follows :M150 designates a lower halfor member. of a diaphragm chamber, the other half of which is shown at151, said members being connected by headed bolts 152 and nuts thereon,said members clamping between a flexible diaphragm 153 shutting olfcommunication between said members, except as hereinafter described.Integral with the member 150 is an inlet connection 154 having a port155 leading to an opening 156 through the flange of the member. 150leading into a passage 157 in the wall of the member 151, said passage157 communicating with the space in said member 151 above the diaphragm153. The connection 154 is connected to that portion of the pipe 52"Lnearest to and leading from the pump 17a. Connected to the lower member150 is an outlet connection 158 (Fig. 5) opening into the lower chamberof the device below the diaphragm 153, said connection 158 beingconnected to that part of the pipe 52"L leading from said regulator tothe burner 16a. The chamber in the upper member 151 above the diaphragm153 opens through a port 159 into a valve casing 160, preferably formedintegral with the member 151, and containing a tapered turn-plug valve161, the latter having a port 162 adapted to communicate with the saidport 159, and leading to the internal bore 163 of the valve, which inturn communicates with a passage 164 leading into the member 150 beneaththe diaphragm 153. In order to provide for a tight lit, the valve 161 ispreferably tapered and fitted to a correspondingly tapered bore in thecasing 160 and is urged to its seat by a spring 165 surrounding a stem166 on said valve, and at one end abutting a packing gland 167 threadedinto the casing 160, and at its other end abutting the upper end oi thesaid valve 161. The valve is provided with a head 168 adapted to beengaged by a wrench or other suitable means by which it may be rotated.Connected to the diaphragm 153, in any suitable manner, as at 169, isone end 170 of a rod 171 extending upwards through a stuliing-box 172 inthe upper wall of the member 151, the upper end of said rod 171 beingpivotally connected, as at 173, to a lever 174, one end of which ispivoted as at 175 to the member 151, and the other end of which isconnected to a flexible connection 176 passing upwards over a pulley177, and thence downward to the levers 66 on the shafts 65 operating thedampers 60, 61, 62 in the same manner as described with reference to theform of invention shown in Figs. 1 and 2. The means for connecting therod 171 to the diaphragm, consists of dished plate 170a having a ilange170" secured by a fluid-tight joint to the lower face of the diaphragmby means of screws 17 0c extending through said flange, packing washers170d between the flange and the diaphragm, and threaded into a washer orring 170c on the upper side ol the diaphragm. The dished portion of theplate 170 extends upwards through a central opening in the diaphragm andhas a central opening 170t through which the rod 171 extends, the rodhaving beneath said plate an enlargement or head 171a of greaterdiameter than the opening in said plate so that the rod and plate areconnected. The under side of the plate is closed against leakage by aplate 171D held in place by the screws 170C. On the casing of theregulator is a bracket 17 8 between which and the lever 174 is suitablysupported and held a compression spring 179 tending to move thelever,174 upwards. One end oi the sprin 179 is seated in a spring seat180 supported on one end of an adjusting screw 181 threaded through thebracket 17 8, and by means of which the resistance of the spring 179 todownward movement of the lever 174 may be regulated. rlhe screw 181 maybe locked in adjusted position by a jam nut 182 threaded thereon.Supported by the bracket 178 is a scale member 183 having a scale 184calibrated to indicate gallons per minute or other iuiit of time of'flowoit fuel to the burner, the upper. edge of said lever 174 cooperating asa pointer with said scale. It will be understood that said scale may becalibrated to indicate any useful information measurable by position ormovement of the diaphragm 153. The operation of this device is asfollows The fluid fuel enters the connection 154 and flows through ports155 and 157 into the space above the diaphragm 153, thence through theport 159 and valve ports 162, 163 and port 164 into the space beneaththe diaphragm 153, from which space it 'flows outwards through the pipe52"L to the burner 16a. The. valve 161 is operable tol cause arestriction to the flow between the upper and lower chambers of theregulator having 'the diaphragm between them, so as to create areduction in pressure in the chamber beneath the diaphragm, thisreduction in pressure being employed to cause movement of the diaphragmto operate the lever 174 to control the dampers. 1t will be understoodthat the valve 161 is set so as to result in a restriction giving thedesired difference in pressure between the Huid in the two chambers, andthat any variations of this difference of pressure, due to iiuctuations`in the rate of llow during the operation of the furnace, will operatethe diaphragm to correspondingly regulate the position of the dampers60, 61, 62. The chambers on opposite sides of the diaphragm 153 arepref- CTL ,rably designed so as to be of equal volume and synunetricalin shape so that the effect of the velocity head of the fluid flowingthrough them will not tend to move the diaphragm, any action of thevelocity head on one side of the diaplufagm being counlerbalanced by asimilar action on the other side. The result of the neutralizing orcounterbalancing of the velocity head in the two chambers, is that thediaphragm. is actuated by the difference in total pressure due to therestriction in the passage between the two chanil'iers. 1t will thus beseen that when the steam pressure drops, the valve 22"l will be operatedto increase the amount of fluid flowing from the pump 17 through theregulator 523 to the burner and that the greater the amount of oilflowing through the regulator, the greater will be the difference inpressure between the fluid above the diaphragm 153 and that below saiddiaphragm, resulting in the excess pressure above the diaphragm movingthe rod 171 to swing the lever 171i to operate the dampers (S0, (il, 02to increase the amount of air supply flowing into the furnace. 1f theboiler pressure increases, the opposite operation from that describedtakes place, that is, the regulator 22 operates to reduce the amount offluid flowing through the regulator to the burner, which is followed bya reduction of the difference in pressure between the oil above thediaphragm 153, and below said diaphragm, permitting the diaphragm tomove upwards, whereupon the spring 179 acting against the difference ofpressure in the regulator moves the lever 17e upwards to control thedampers 60, 61, 62 to shut off or reduce the supply of air fed into thefurnace.

lnasmuch as the balanced draftregulator acts in the same manner asdescribed with reference to the form of the invention shown in Figs. 1and 2, it is not necessary to repeat that description here. The valve161 can be so adjusted that the variations in difference of pressure dueto variations of volume of flow which cause the travel of the rod 171,can be made to give the dampers 60, G1 and 62 the desired position fromminimum desired opening to maximum desired 'opening corresponding tominimum flow of fluid fuel to maximum flow of fluid fuel.

The regulator, as shown in Figs. 8, 1l, 5 and 6, is not claimedspecifically herein, but is the subject of a divisional application forLetters Patent, filed by me on or about September 20, 1921, and bearingSerial No. 502,039.

The apparatus for regulating the area of the distribution of the airsupplied to the furnace is the subject of a divisional application forLetters Patent, filed by me on or about October 6, 1921, Seral No.505,804.

lVhat I claim and desire to secure by Letters Patent of the UnitedStates is 1. The method of operating a fluid fuel burning` furnace whichconsists in controlling the air entering the furnace in accordance withthe rate of flow of fluid fuel supplied to the furnace, and controllingthe outflow of gases to maintain a substantially constant pressure inthe furnace chamber for varying` rates of air supply.

2. The method of operating a fluid fuel burning furnace which consistsin controlling the air entering the furnace in accordance with the rateof flow of fluid fuel suppliei'l to the furnace, and controlling theoutflow" of gases in accordance with varying rates of air supply tomaintain a substantially constant pressure in the fr chamber for varyingrates of air supply.

3. The method of operating a fluid fuelfired furnace which consists incontrolling the area of the. distribution of air supplied to the furnacein a-ccordance with a characteristic of the flow of fluid fuel suppliedlo the furnace.

1. r1`he method of operating a fluid fuelfired furnace which consists incontrolling the area of the distribution of the air supplied to thefurnace in accordance with the rate of flow of fluid fuel supplied tothe furnace.

5. The method of operating a fluid fuelfired furnace which consists incontrolling the area` of the distribution of air supplied to the furnacein accordance with a characteristic of the flow of fluid fuel suppliedto the furnace, and producing a flame, the surface of which is directlyproportional to the amount of fluid fuel supplied to the furnace.

(i. The method of operating a fluid fuelfired furnace which consists inautomatically controlling the area of the distribution of air suppliedto the furnace in accordance with a characteristic of the flow of fluidfuel supplied to the furnace, and producing a flame, the surface ofwhich is directly proportional to the amount of fluid fuel supplied tothe furnace.

7. The method of operating a fluid fuel burning furnace which consistsin supplying fluid fuel and air for combustion to the furnace, andregulating the combustion in accordance with the rate of flow of fluidfuel fed to the furnace.

8. The method of operating a fluid fuel burning furnace which consistsin supplying fluid fuel to the furnace chamber to be burned therein,supplying air to the furnace chamber for combustion, and regulating thesupply of air in accordance with the rate of flow of fluid fuel fed tothe furnace.

9. The method of operating a fluid fuel furnace, which consists inintroducing air for combustion through a plurality of areas, andcontrolling the air supplied through the various areas in accordancewith a characteristic of the flow of fluid fuel supplied to the furnace.

l0. The method of operating a fluid fuel 5 furnace, which consists inintroducing air for combustion through a plurality of areas,

and controlling the air supplied through EMBURY MCLEAN.

the various areas in accordance with the rate of the flow of fluid fuelsupplied to the furnace. 10

In testimony whereof I have hereunto signed my name.

